As a freshly minted Asiana Club Diamond member (=*A Gold), I'll try here to explain how it works.
Firstly, previous posters are correct to point out that the points you receive for your flight is determined by the booking class code your ticket is under. For Asiana, the table is here:
Asiana Airlines
I strongly suspect that the percentages are determined by the flying airline than by Asiana Club itself and are similar, if not identical, for all *A FF programs. So, for example, United is relatively generous with points (although some may suggest that you pay by other means....) while Egyptair is somewhat less so. This is mainly an issue for flying in economy. Business and first class travel (unless done by points) gets points every time, it would seem, at a minimum of 100% (usually Business = 125%, First = 150%).
The two main advantages with Asiana Club from my viewpoint (self funded long haul international travel once to twice per year on average) is the lower mileage requirements for status (20,000 mi = OZ Gold = *A Silver, 40,000 mi = OZ Diamond = *A Gold (over two years), 500,000 mi = OZ Diamond Plus = *A Gold (for life)). and the long expiry dates for points. All members get at least 7 years before their miles expire. OZ Gold get 10 years (include all previously earned miles) and all superior tiers get 12 years. Given that my travel type stated above is only an average and there might be a gap between flights, the fact that my miles won't disappear after only three years is a big selling point for me.
There is no such thing as status credits in this program, or any other *A program, as far as I know (in fact, I hadn't heard about them until I found this forum since I haven't flown QF for 15 years). For all the Asiana Club tiers, one can qualify by flying x number of flights on Asiana ONLY (Gold = 30, Diamond = 50 and so on) but unless you plan on doing alot of flying in South Korea, qualifying by miles is much more realistic. The only other issue here is that Asiana is also partners with Qatar Airways, Etihad Airways and EVA Air. These three are not part of *A (although EVA will be joining in mid 2013, so the following won't apply for them soon). For flights on these airlines, you get miles (based on booking class) to use for flight rewards, but these miles DO NOT count towards your Asiana Club or *A status. So, despite all of their virtues, these airlines are no good for a status run on the Asiana Club program. You can however redeem miles for tickets on these airlines.
Apart from the universal benefits of *A tiers, there are specific benefits for reaching tiers with Asiana Club. For OZ Gold, you get a 5,000 mile discount voucher and two Asiana lounge vouchers (to only be used with Asiana, valid for 12 months) and a nifty baggage tag (looks a bit better and sturdier than the paper ones at the check in counter at any rate!). Having just reached OZ Diamond, I will soon receive a voucher for either 10,000 miles or a half points seat upgrade on OZ flights. Finally, there is a bonus added to all miles earned on OZ flights depending on tier (OZ Gold = +5%, OZ Diamond = +10% and so on).
Overall I'm pretty happy with the program given that I'm not a hyper frequent flyer (or one that can afford to sit up front). Definitely the long expiry dates for mile redemption is a major plus in my book. Apart from their lovely on board product and service, they were also very helpful when one of my flights (NZ8, AKL-SFO) didn't go through to my account. I just handed over my boarding pass stub from that flight, a flight itinerary from when I purchased the ticket and signed a form at their counter at PVG and the miles where in my account within the week. No inquisitions, no complaints.
